In the light of your oil sample test results, I think you should first attempt to establish if you have a mechanical/hydraulic fault with your transmission, for example with the A clutch.

Your 5HP24’s hydraulic system was designed in such a way that, in the event of complete electrical/electronic failure (i.e. none of the solenoids working), it engages 4th gear (A & B clutches applied) when D is selected and reverse gear (C & F clutches applied) when R is selected.

To try to simulate this failure you can temporarily disconnect the 16-pin connector at the rear of the transmission.

Could you maybe try this and report back whether or not your E53 successfully pulls away in 4th gear? This would tell us if the A clutch is still functioning.

While you’re under there, could you also make a note of the transmission’s serial number from the green i/d plate rivetted to the LH side of the maincase, adjacent to the 16-pin connector?



Phil